The invention concerns a nuclear power plant arranged in an underground cavity comprising a small high-temperature pebble bed reactor; a reactor core; spherical operational elements which pass through the core more than once; a steel reactor pressure vessel in which the small high-temperature reactor and a heat exchange apparatus are installed; and a loading installation for the addition and removal of fuel elements.
A nuclear powe plant of this type is described in German patent application No. P 33 35 451.0. In this nuclear power plant, all of the components of the primary loop, together with the control and shutdown installations are disposed within a steel reactor pressure vessel in such a manner that they may be installed and removed from above. This renders an economical underground construction possible. Under the small reactor, at least one discharge tube is provided for the removal of the spherical fuel elements.
Another nuclear power plant with a small high-temperature reactor suitable for installation in an underground cavity is described in German patent application No. P 33 45 113.3. Here again, the spherical fuel elements introduced on top are drawn off by means of a discharge device at the bottom of the pile.
Loading installations for nuclear reactors of medium capacity with spherical fuel elements which are built by the principle of modular construction are known. These installations comprise movable functional parts for the addition, removal, distribution and extraction of fuel elements by means of drives. The functional parts are provided with bores for the passage of fuel elements and are set into a block, or plate equipped with connecting bores for the fuel elements. Feed installations of this type are described in German Gebrauchsmuster No. 6 753 677, German Auslegeschrift No. 15 89 532 and German Offenlegungsschrift No. 23 57 426. The manner in which the introduction of the fuel elements into the reactor core is effected, is not disclosed in the references cited.
The state of the art further includes German Pat. No. 1 281 046, which again concerns the feed installation of a so-called pebble bed reactor of intermediate capacity. The discharge and sorting installation for the spherical fuel elements is located under the reactor core. It contains a measuring device in which the fuel elements are examined with regard to their state of depletion. Depending on the results of the measurement, the fuel elements are either returned into the reactor core or eliminated from the circulation of fuel elements. The addition of fresh fuel elements is effected from above through a feed tube. The installation and removal of primary loop components is thus rendered difficult.